In connection with transport, handling, processing etc. of various items including food items such as pieces of meat, fish, pieces of poultry etc., it is desired to be able to grip and move or transport such pieces further on one by one. In particular this will be the case when such items are delivered in an un-orderly form, possibly with a plurality of items being accumulated or piled up, and similarly, when it is of importance, for example in consideration of a further processing of the items, that the items are transported further on with a certain minimum distance between the items.
It is known to use various forms of vacuum transport devices in such instances.
Such devices are disclosed for example in EP 619249 A1, EP 1021361 B, NL 9102028 og WO 2005/035405 A1. These prior art devices all have an external suction pump or the like, from which vacuum is led to the devices. Such vacuum devices require frequent cleaning, when used for transporting food stuff or the like, which may be troublesome and may demand considerable resources, if a satisfactory result is to be achieved.
Further, these prior art devices are characterized in having the lifting means arranged in a static configuration. EP 619249 A1 and EP 1021361 B describe the lifting means being mounted in a horizontal wheel configuration, meaning that the individual lifting means are moved circularly in a horizontal plane. NL 9102028 and WO 2005/035405 A1 describe the lifting means being mounted in a drum- or wheel-shaped arrangement, which on its surface is provided with suction holes, by means of which items may be gripped and moved one by one.
Furthermore, various mechanisms are used at these prior art devices in order to ensure that vacuum is connected at the right time and that vacuum is disconnected at the right time in order to release the items. Such mechanisms may add to the complexity of the design and may furthermore hinder or make an efficient cleaning difficult.
Furthermore, vacuum devices are known, which are used for lifting individual items without using external vacuum sources.
For example, EP 1 484 142 A1 describes a vacuum lifting device, where a piston can be moved downwards in a cylinder by means of compressed air and where the piston can be moved upwards by means of a spring. The cylinder has at its lower end a channel, which leads to a suction disc. This prior art lifting device is used by removing the pressure, i.e. the compressed air, whereby the spring will lift the piston upwards, thus resulting in a vacuum being produced in the cylinder, whereby an item such as an optical lens can be withheld to the suction disc.
A similar lifting device is known from EP 1 477 439 A1, where, though, the piston can also be forced downwards against the spring force by means of an electromagnet.
Both of these prior art lifting devices are adapted for lifting solid, mechanical stable items and thus a predetermined piston stroke is used in order to produce a vacuum having a predetermined value. Furthermore, both of these devices are designed in such a manner that apparently there is no possibility of separating cylinder and piston, meaning that it is not an option to use such devices for applications, where the hygienic condition has to be considered.
It is a further common characteristic for the abovementioned prior art devices that the number of items that may be gripped and moved, is limited, thus meaning that these prior art devices are insufficient when it is desired to move a plurality of items with a desired velocity, corresponding to the velocity, by which such items are transported in for example the field of foodstuff processing.
Still further, devices are known for moving a relatively large number of items simultaneously, for example glass items or the like, which in advance have been placed in an orderly form, for example placed in one or more rows, where a shared carrier has a corresponding large number of suction means arranged in a corresponding manner, and where the suction means all are connected to a shared vacuum source. It is obvious that such a device is not suitable for moving items individually, but for moving a relatively large number of items simultaneously, which items have to be placed in an orderly form in advance. Furthermore, the device is not designed to be able to deliver the items at different points in time, since the items are released all at the same time.
Thus, it is an object of the invention to provide a method and a system for transferring items individually, which provide an improvement in relation to the prior art and without the abovementioned drawbacks.
Furthermore, it is an object of the invention to provide such a method and such a system for gripping items one by one from an un-orderly flow or bulk and moving these to another flow, where the items are delivered. A particular object is to provide such a method and such a system, where vacuum is used for lifting the items. A further particular object is to provide such a method and such a system where the use of an external vacuum source may be avoided.
A still further object is to provide such a method and such a system, which are flexible.
Another object is to provide such a method and such a system, by means of which an enhanced capacity may be achieved in relation to the prior art, and by means of which a transfer speed may be achieved corresponding to the process speed currently used in the field of food processing, even when a large number of items are handled, thus achieving that such a method and such a system may efficiently be used in such applications and that the method and the system may readily be adapted for handling the number of items that are actually being fed.
A still further object is to provide such a method and such a system, where cleaning may expediently and efficiently be taken care of.
It is also an object to provide such a method and such a system, which is designed for use in connection with items, e.g. food items or the like, which not necessarily are provided with a stable or firm form and/or structure.
These and other objects are achieved by the invention as it will be explained in the following.